Method VariableUint

utils/reader.go:129–193

VariableUint reads a uint64 that was written using variable-length encoding.

()

// VariableUint reads a uint64 that was written using variable-length encoding.
func (reader *Reader) VariableUint() uint64 {
	// This has been adapted from one of our blogs:
	// https://www.dolthub.com/blog/2021-01-08-optimizing-varint-decoding/
	b := uint64(reader.buf[reader.offset])
	if b < 0x80 {
		reader.offset += 1
		return b
	}
	x := b & 0x7f
	b = uint64(reader.buf[reader.offset+1])
	if b < 0x80 {
		reader.offset += 2
		return x | (b << 7)
	}
	x |= (b & 0x7f) << 7
	b = uint64(reader.buf[reader.offset+2])
	if b < 0x80 {
		reader.offset += 3
		return x | (b << 14)
	}
	x |= (b & 0x7f) << 14
	b = uint64(reader.buf[reader.offset+3])
	if b < 0x80 {
		reader.offset += 4
		return x | (b << 21)
	}
	x |= (b & 0x7f) << 21
	b = uint64(reader.buf[reader.offset+4])
	if b < 0x80 {
		reader.offset += 5
		return x | (b << 28)
	}
	x |= (b & 0x7f) << 28
	b = uint64(reader.buf[reader.offset+5])
	if b < 0x80 {
		reader.offset += 6
		return x | (b << 35)
	}
	x |= (b & 0x7f) << 35
	b = uint64(reader.buf[reader.offset+6])
	if b < 0x80 {
		reader.offset += 7
		return x | (b << 42)
	}
	x |= (b & 0x7f) << 42
	b = uint64(reader.buf[reader.offset+7])
	if b < 0x80 {
		reader.offset += 8
		return x | (b << 49)
	}
	x |= (b & 0x7f) << 49
	b = uint64(reader.buf[reader.offset+8])
	if b < 0x80 {
		reader.offset += 9
		return x | (b << 56)
	}
	x |= (b & 0x7f) << 56
	b = uint64(reader.buf[reader.offset+9])